Australian swimming sensation Ian Thorpe has made history by claiming a record sixth gold medal at the World Championships in Fukuoka.

Speaking after he anchored the 4x100m medley relay team to victory on Saturday Thorpe joked: "I am pretty disappointed really.

"But I should not joke because I am more than pleased with how I swam.

"To be able to walk away from this meet having done so well is very satisfying."

The Australians fought a tight race with the United States only for the Americans to be disqualified, along with the Netherlands, for faulty take-overs on the final
freestyle leg.

The race itself had been a great duel, with Matt Welsh leading for Australia on the opening backstroke, American Ed Moses moving up from fifth to first on the breaststroke before
Geoff Huegill got the lead back for Australia on the butterfly.

Anthony Ervin rocketed past Thorpe on the first length of the concluding freestyle but the Australian just caught him at the final touch.

The Australians had to then wait for several minutes before their win was confirmed.

The official results indicated that Ervin and Dutch Olympic champion Pieter van den Hoogenband, the 100m freestyle gold and silver medallists on Friday, had taken off too soon.

Huegill also took gold in the 50m butterfly

Thorpe is the first swimmer to win six gold medals at a single world championships, beating the previous record of five set by Jim Montgomery in 1973 and Tracy Caulkins in 1978.

Australia won the race in a time of 3:35.35 seconds, Germany moved up for the silver in 3:36.34 and Russia the bronze in 3:37.77.

Saturday's relay victory also capped off a good day for Huegill who had earlier claimed gold in the 50m butterfly.

Australian women also had plenty to cheer about as Petria Thomas completed a golden double winning the women's 100m butterfly final.

Thomas, who won the 200m butterfly on Monday, won in 58.27 seconds.

Poland's Otylia Jedrzejczak took the silver in 58.72 and Japan's Junko Onishi had the home crowd cheering on her way to the bronze in 58.88.

Hannah Stockbauer of Germany took gold in the 1500m freestyle event in 16:01.02.

Switzerland's Flavia Rigamonti finished second in 16:05.99 with American Diana Munz third in 16:07.05.

The American Natalie Coughlin took the gold in 100m freestyle in 1:00.37 seconds.

Romania's Diana Mocanu claimed the silver in 1:00.68 and Antje Buschschulte of Germany the Bronze in 1:01.42.